Discharge tube



Oct. 1, 1940.

A. MUTSCHELLER- mscnmem TUBE Original Filed Dec. 10, 1937 IN V EN TOR.

Patented Oct. 1, 1940 PATENT or'ricr.

DISCHARGE TUBE Arthur Mutscheller, New York, Y.

Application December 10, 1937, Serial No. 179,094

Renewed March 4, 1940 5 Claims. (01. 250-2125) This invention is for animproved high voltage current rectifier of the hot cathode type havingmany valuable features and advantages over the old known system ofemploying several single 5 rectifier units for accomplishing the sameresult.

More specifically stated, I have discovered how a number of rectifiersof the high vacuum type can be combined into one unit and therewith thesame result obtained as with the much more 10 cumbersome and expensiveold system in which several rectifiers must be interconnected, me-

chanically assembled and insulated from each other.

. As an example, we have in the well known 15 Graetz system forrectifying high voltage alternating current,- a transformer havingconnected to each of its high voltage producing terminals two valvetubes one with its anode and the other with its cathode. The free anodesof these two 20 pairs of valve tubes and alsothe free cathodes areconnected together and from these then a high voltage pulsatingunidirectional current is obtained. This kind of rectified high voltagecurrent is usable for many purposes as for the 25 excitation of X-raytubes, dust precipitation, furnishing of plate voltage to radio circuitsetc.

To obviate the requirement of connecting, supporting and insulating fromone anotherof four tifier mounted in one envelope can be con structed.

40 Fig. 1 shows diagrammatically how, with a diaphragm of insulatingmaterial, and by operating at least one set of electrodes at voltagesaturation the short-circuiting of electrons from one of the inletelectrodes directly over to the other 45 can be prevented. a

Big. 2 shows, diagrammatically, how with specially constructed anodesalternating current can be rectified without the electronsshort-circuiting from the cathode of one inlet terminal to the 5 anodeof the other inlet terminal.

. Fig.3 is a diagrammatic illustration of an anode and a cathode withwhich the escape of electrons to the outside of the cooperating anode isprevented.

5 Fig. 4 shows, diagrammatically, how an X-ray tube can be constructedin which both alternating current impulses are utilized for theproduction of X-rays and how the direct passage of electrons from oneinlet electrode to the other has been avoided. I 5

If electrons should directly traverse the evacuated space, for instancein Fig. 2 from cathode ll to anode llhthcn there could be norectification as it is intended and the circuit through the dischargedevice would be short-circuited Without delivering rectified current tothe outlet terminals fill and ill. Therefore, this direct transfer ofelectrons from one inlet terminal to the other must be prevented.

How this can be done is shownin the diagram Fig. l, which shows-two waysof preventing electrons from passing directly or short-cir cuiting forexample from the cathode of one of the inlet terminals to the anode ofthe other inlet terminal. One way is to place the inlet cathode andanode in compartments separated by a septum or partition of dielectricmaterial as here, the anodes 3| and 3% are on one side of the partition39 and the cathodes 3t and 35 are on the other side of it. Therefore,instead of a direct discharge from cathode 35 to anode ill, or fromcathode 34 to anode 3d, the discharge must first be between cathodedfiand anode 33 then from cathode 32 to anode 3i or from cathode 3:1 toanode 33 and from cathode 32 to anode 3t, and the current flowing in theoutside circuit from anodes 33 to the cathodes 32 is thenunidirectional. The other way is to operate the discharge from cathodesMend 35 to the anodes 33 at voltage saturation and the discharge fromthe cathodes 35 32 to the anodes 3i and 36 below voltage saturation andtherefore so that the electron emission from the. cathodes 32. is largerthan that from the cathodes 3i and and that the voltage applied to theterminals til and 31 is sufficiently high to produce voltage saturationbetween cathodes 34 and'35 and the anodes 33.

In Fig. 2 and Fig. 3 a third way of preventing the. direct a passage ofelectrons between the cathodes and the anodes of the inlet terminals isillustrated. The anodes l2, l6, l8 and 1B are of special design so thateven if operated below saturation, the direct passage of electrons fromone of the inlet terminals to the other is prevented. These anodes areshaped to surround the coop- 5o crating cathodes to such an extent, thatthe negative potential onthe lead-in wires to the emittingcathode whichpass through the center of openings in the anode is sufficient toprevent the escape of electrons along the lead-in wires and out of theenclosing anode. Thus the electron emitting cathodes 14, 13, 11 and 15are caged-up within the receiving anodes 12, 19, 18 and 16 and theconstruction of the opening in the anode is so adjusted, that itsdiameter is smaller than the inside diameter of the anode. Still, if theanode is made tubular having a length dimension in the direction of thecathode lead-in wires greater than the diameter and closed at one end,it may not be necessary to make the opening for the cathode lead-inwires smaller than the lumen of the tubular anode.

In Fig. 2", two pairs of such anodes surrounding the cooperatingcathodes: are shown connected to form an alternating current rectifierwhich operates on the principle above outlined. The inlet terminals 82and H receive alternating current impulses; the negative impulse fromterminal 82 passes from cathode TI to anode 18 out through outletterminal 89 through an outside circuit back to inlet terminal 8| fromcathode 14 to anode 12 to inlet terminal ll. Or, if terminal H isnegative, the electrons pass from cathode 13 to anode 19 to outletterminal 80, through an outside circuit back to terminal 8!, fromcathode 15 to anode !6 to inlet terminal 82. The opening in the anodesand the diameter of the cathode lead-in wires must be so adjusted, thatif the voltage in the outside circuit is as large as that of thealternating current in-put, that no electrons can escape from the anodesthat encage the cooperating cathodes.

How this is done is illustrated in the diagrammatic Fig. 3. The anode 99supported on a stem 9| is spherical and provided with an opening havingrounded and extended edges 92 which is smaller in diameter than thespherical anode. The cathode 96 is either a flat spiral, loops or amushroom-shaped coil to leave a substantially equally spaced distancebetween the cathode and the anode; The cathode is supported by thelead-in wires 93 and 94 and a disc having rounded edges 95 may be placedso as to form an electrostatic shield to prevent electrons from escapingthe anode. The enclosing anode, therefore, shields off all outsidefields and the shield increases the electrostatic shielding effect ofthe cathode lead-in Wires which are negatively charged so that noelectrons can get out of the anode no matter how high the positivepotential on the anode of the other inlet terminal may be.

The aforegoing description should serve to show, that there are numerousways of preventing the direct passage of electrons from the cathode ofone of the inlet terminals to the anode of the other inlet terminalwhich are connected to the alternating current source. Several of thesehave been described and illustrated. For instance by shielding withdielectric substance in Fig. l; by operating, at least one pair ofcathodes and anodes at saturation as is shown in Fig. 1, where thedischarge from the cathodes 34 and 35 is controlled directionally with afocusing device 39 so that the discharge therefrom will fall uponananode placed into the path of the accelerated cathode stream, and thenadjusting the cathodes 32 to operate with the cooperating anodes belowvoltage saturation so that the voltage drop between these is less thanthe voltage drop between the cathodes 34 and 35 of the inlet terminalsand the anodes 33; or the anodes may be formed to surround the electronemitting parts of the cathodes as shown in Fig. 2 and Fig. 3 to theextent that no electrons can be pulledout oi the surrounding anode evenif the voltage delivered into the Working circuit in the form ofunidirectional pulsating current impulses is equal to the voltage of theenergizing alternating current. This same object may be obtained byproviding a third or grid electrode having a voltage that prevents anyelectrons from escaping from within the anode through the openingthrough which the cathode lead-in wires are passing. All these aremethods which in principle are well understood in the art and which anyperson skilled in this art can carry out successfully with theseinstructions Without requiring further aid or instruction.

Having thus described several ways according to which my invention canbe carried out, I hereby declare that other ways may exist with whichthe same results may be obtained and which may be substituted for thoseherein disclosed without having to do additional inventing.

Therefore, I claim,

1. An electric discharge tube comprising an envelope having therein amain anode having hollow electron receiving sections and a mainthermionic cathode having electron emitting sections, an auxiliaryhollow anode substantially enclosing each of said electron emittingsections, additional thermionic cathodes each being substantiallyenclosed by one of said hollow electron receiving sections, independentleads connected tween each auxiliary hollow anode and one only of saidadditional thermionic cathodes.

2. An electric discharge tube comprising an envelope having therein amain anode having electron receiving sections, and a main thermioniccathode having electron emitting sections, an auxiliary anode adjacenteach of said electron emitting sections, additional thermionic cathodesbeing adjacent to said main anode and each having a focusing shieldabout each of said additional thermionic cathodes to direct the electrondischarge therefrom upon the electron receiving sections of said mainanode, independent leads connected to said main cathode and to each ofsaid auxiliary thermionic cathodes, a conductive lead between said mainanode and said main cathode and a conductive connection between eachauxiliary anode and one only of said additional thermionic cathodes.

3. An electron discharge tube comprising an envelope having therein amain anode having electron receiving sections, and a main thermianodeand one only of said additional thermionic cathodes, and a partition ofdielectric material between non-adjacent electrodes as a shield againstelectron discharges between non-adjacent anodes and cathodes.

4. An electric discharge tube comprising an envelope having therein amain anode having electron receiving sections and a main thermioniccathode having electron emitting sections, an auxiliary hollow anodesubstantially enclosing-each of said electron emitting sections, ad-

ditional thermionic cathodes each being adjacent one of said electronreceiving sections and having a focusing shield for directing theelectron discharge upon said main anode, independent leads connected tosaid main cathode and to each of said thermionic cathodes, a leadconnecting said main cathode and said main anode together, and aconductive connection between each auxiliary hollow anode and one onlyof said additional thermionic cathodes.

5. An electron discharge tube comprising an envelope having therein amain anode having electron receiving sections, and a main thermioniccathode having electron emitting sections,

an auxiliary anode adjacent each of said electron emitting sections,additional thermionic cathodes one adjacent each of said electronreceiving sections, independent leads connected to said main and to eachof said additional thermionic cathodes, a lead connected to said mainanode, a conductive connection between each auxiliary anode and one onlyof said additional thermionic cathodes, there being means for preventingelectronic discharges between said ad- 10 ditional cathodes and saidauxiliary anodes.

ARTHUR MUTSCHELLER.

